Roof structure



FIG. 1 is an elevational view of a front of a roof structure showing our new design;

FIG. 2 is an elevational view of a rear of the roof structure;

FIG. 3 is an elevational view of a left side of the roof structure;

FIG. 4 is an elevational view of a right side of the roof structure;

FIG. 5 is a plan view of a top of the roof structure; and,

FIG. 6 is a plan view of a bottom of the roof structure.

The broken lines illustraitng a building is for illustrative purposes only, and forms no part of the claimed design. 

The ornamental design for a roof structure, as shown and described. 